A ferrite core having a platform, disclosed in Japanese Unexamined Patent Application Publication No. H02-91903, is known as an example of a past disclosure regarding an electric circuit. This ferrite core includes a cylindrical ferrite core main body and a platform provided with a screw hole. A cable containing a power source line, a ground line, a signal line, and the like passes through the interior of the ferrite core main body. The ferrite core is attached to a chassis or the like of an electronic device by a screw inserted into the screw hole. This ferrite core is capable of removing common mode noise flowing in the power source line, the ground line, the signal line, and the like.
Incidentally, the ferrite core disclosed in Japanese Unexamined Patent Application Publication No. H02-91903 is attached to the cable so as to surround the periphery of the cable. A large space is therefore required to place the ferrite core, which makes it difficult to use the ferrite core inside an electronic device.